Don't include scroll offset in offsetFromLayoutObject for scrolling contents layers.

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
index 9081857db32c0caf9d08620a6d0a46f5ebc4eb72..5c120076b33835c490d583731d8f131c98d821d4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
@@ -412,7 +412,7 @@ void LayoutBoxModelObject::invalidateTreeIfNeeded(const PaintInvalidationState&
     invalidatePaintOfSubtreesIfNeeded(newPaintInvalidationState);
 }
 
-void LayoutBoxModelObject::setBackingNeedsPaintInvalidationInRect(const LayoutRect& r, PaintInvalidationReason invalidationReason, const LayoutObject& object) const
+void LayoutBoxModelObject::setBackingNeedsPaintInvalidationInRect(const LayoutRect& r, PaintInvalidationReason invalidationReason, const LayoutObject& object, bool scrollingOnly) const
 {
     // TODO(wangxianzhu): Enable the following assert after paint invalidation for spv2 is ready.
     // ASSERT(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
@@ -429,7 +429,10 @@ void LayoutBoxModelObject::setBackingNeedsPaintInvalidationInRect(const LayoutRe
             squashingLayer->setNeedsDisplayInRect(enclosingIntRect(paintInvalidationRect), invalidationReason, object);
         }
     } else {
-        layer()->compositedLayerMapping()->setContentsNeedDisplayInRect(r, invalidationReason, object);
+        if (scrollingOnly)
+            layer()->compositedLayerMapping()->setScrollingContentsNeedDisplayInRect(r, invalidationReason, object);
+        else
+            layer()->compositedLayerMapping()->setContentsNeedDisplayInRect(r, invalidationReason, object);
     }
 }